This invention relates to the composition of propellants and more particularly to the field of solid propellants used in rockets. When used in a propellant formula glycidyl azide polymer (GAP) decomposes exothermically to give a high yield of permanent gases due to decomposition of the azido group which releases of 80Kcal/mol of CN bond. However, GAP and curatives have a tendency to evolve CO.sub.2 with acidic deflagrating additives when they are used along with them to form combustible gas generant formulations. Also the isocyanate curatives generally used in GAP formulations react with acidic deflagrating additives such as acidic tetrazoles to produce CO.sub.2, with the result that a porous propellant with erratic burning rates is produced. Formulations with GAP and high nitrogen solid additives provide exceptionally good rubbery propellants with high gas yield, tailorable burning rates and relatively cool flame temperature. It is therefore highly desirable to prevent gassing in formulations using acidic oxidizers. Therefore it is the object of this invention to provide void free propellants.